This invention relates to aqueous ink jet inks and more particularly, aqueous inks containing polymer/dye reaction product and having improved chroma.
Ink jet printing is a non-impact method for recording information in response to an electronic signal, such as that generated by a computer. It has become increasingly popular, particularly for so-called "desk-top publishing", because of its capability to produce small volumes of printed matter from digital input, at high throughput speeds with reliability, relatively quiet operation, good print quality, and at low cost. In the printer, the electronic signal produces droplets of ink that are deposited on a substrate such as paper or transparent film. Thermal or bubble jet drop-on-demand printers have been especially successful and have found broad application as output devices for personal computers in the office and the home.
Both dyes and pigments have been used as ink colorants for ink jet printers. However, dye-based inks have several disadvantages as compared to pigment-based inks. They are usually very water soluble and remain so after drying on the substrate. They are easily re-dissolved by contact with water and will run when exposed to a water spill. Also, dye images smear on contact with felt pen markers. In addition, they exhibit poor light stability relative to pigments and are known to fade even under conditions of office fluorescent lighting. Thus, dye-based ink jet inks are often unsuitable for use in applications requiring moisture resistance and greater light stability.
Pigments, however, provide improved water and smear resistance and improved light stability. However, they do not have the required chroma that is one of the major advantages of using dyes.
Thus, there is a need for improved inks that have good water and smear resistance, improved light stability and also good chroma.